Hydraulic hoist



R. E. CHOATE HYDRAULIC HOIST Jan. 3, 1933.

Filed June 24, 1929 Patented Jan. 3, 1933 UNITED STATES ROY E.- GHOATE, OF CEDAR RAPITjS, IQ WA nYnRAuLIc' noisr' Application file-d June 24,

This invention relates to hydraulic lifting mechanism, and more particularly that type of the same illustrated and described in a former application for patent by this inventor for improvements in dump wagons, being Serial No.367,903,filed June 3,1929; In such former application the hoisting mechanism is applied to the lifting and sustaining of the dump-doorsof the wagon, and while the apparatus is shown and described in detail, it is only claimed in combination with the dumpwagon and its trapdoors. Substantially the same illustration and description will apply to the present application, but the claims are directed to the specific hoist, which is adapted to manifold purposes.

The objects of the invention will be sufliciently apparent from the description and claims following, reference being had to the accompanying drawing, in which:

Fig. 1 is a side elevation of a hydraulic hoist embodying the invention. Fig. 2 is a plan view of the same. Fig. 3 is a central, vertical section of the same, some of the parts shown in Fig. 1 being omitted.

In the drawing, the numeral 5 is supposed to designate the front end of a dump-wagon and 6 the tongue for the wagon, which parts may serve to conveniently illustrate the mounting and operation of the hoist. The wagon, as fully set forth in said former application, is supposed to be drawn by a tractor, not herein shown, and the tractor is supposed to carry and operate. an oil-pump and accessories for supplying oil under high pressure to the hydraulic Jack hereinafter described.

To the tongue, which may serve as a typical base or support, is securely bolted at 7 and 8, a hydraulic jack. This'includes a pressure cylinder 9 having a head 10 through which the pressure oil is received from a service pipe 11 assumed to be in operative connection with the pressure pump above mentioned. The other end of the cylinder connects with a housing 12 provided with lateral bearings 13 for a cross-shaft 14. As herein illustrated the shaft carries a pair of cable-drums, 15 and 16, respectively. One of the drums is formed in part as a ratchet 17, which with ac- 1929. .Serial No. 373,450.-

companying details will be more fully de scribed presently. Near the rear end of the housing is formed an abutment 18 (Fi 3)., and through this passes the rod 19 o the pressure piston 20. On the reduced end of the piston-rod is mounted aslip-collar 21, and between this and an end-collar or nut 22, fast to the piston, is mounted a coil spring 23. The purpose of this spring is to cushion the back-stroke of the piston when the oil-pressure is released and the weightof the load is transmitted to the piston through the hoisting mechanism to be described hereafter. This part of the piston-rod and its connections is protected against injury, by a pipe 24, the cap of which is perforated to permit the passage of air, as shown in Fig. 3.

Rigidly fixed to the shaft 14 is a spur gear 26, which is made to mesh with the teeth of a rack 19aformed on one side of the pistonrod. The in-thrust of the piston thus transmits rotary motion to the cable drums attached to the shaft. A hoisting cable 27 is shown attached to the drum 16, and trained over a sheave 28, which latter may be mounted on any stable support.

A bracket 29 projecting from the top of the housing forms a support for a depending pendulum arm 30, which is cored at 30a to receive a pawl 31. The pawl has a tail 31a which serves both for gravity to hold the pendulum and pawl in position for engagement with the ratchet by preponderating weight, and as a lever for disengaging the pawl. In its terminal eye 31?) is connected a pull-cord or chain 32, which is trained over a sheave 33 and is supposed to extend forwardly to a point where it may be manipulated by the operator of the tractor. It will be noted that in the engaging position shown in Fig. 1 the point of the pawl is almost exactly in line with (preferably slightly back of) the line a, b from center to center of the pendulum pivot30c and the pawl pivot 310. Any further backward movement of the pawl with respect to the pendulum is prevented by the contact of the heel 31d of the pawl with an abutment 34 at the lower, for- Ward end of the pendulum. Thisis preferably a screw in the end of the pendulum, and

may be adjusted with the greatest nicety to regulate the position of the point of the pawl with respect to the line above mentioned.

In many operations, it is desirable to drop the load suddenly, which is practically impossible if the action depends solely on the retreat of the hydraulic piston. Accordingly, in the operation of this device and considering that it is being utilized to lift the trap doors of a dump wagon to load-supporting position, pressure is admitted to the hydraulic cylinder 9 through a valve 35 of the three-way type, accessible to the driver of the tractor, and the ensuing movement of the piston revolves the drum to wind up the cables. At the limit of movement, the ratchet is caught by the pawl and the cables which are connected to the doors are held by the drum. Thereafter, "the hydraulic hoist may be released by another movement of the fluidadmitting Valve (not shown) to permit the escape of the pressure fluid in the hydraulic cylinder and subsequently to permit a quick dumping movement of the doors by merely retracting the latch mechanism. Applicants arrangement is such that the ratchet and pawl entirely support the load after the release of the pressure fluid and they are further so disposed as to permit their easy withdrawal from the load-sustaining position.

It is further to be noted that the construction is such that there is little or no danger of breakage, even by false motions on the part of the operator. It will be evident that when the pawl is tripped the pendulum is forced backwardly, in which direction it is free to move indefinitely. At the same time the point of the pawl is carried downwardly by the ratchet until the tail strikes the bridge 30d, when the point of the pawl may jump from tooth to tooth of the ratchet without injury.

I claim:

1. A hydraulic hoist comprising a pressure cylinder, a piston and its rod mounted therein, one side of the rod being formed as a rack, an engaging pinion imparting rotary motion to a cross-shaft and hoisting drum, an abutment traversed by the piston rod, and a compression spring carried by the piston rod and adapted to cushion the backstroke thereof in conjunction with said abutment.

2. A hydraulic hoist comprising a pressure cylinder, an adjacent housing, a crossshaft mounted therein, a pinion fixed to the shaft, a piston and rod in said cylinder. the rod being formed on one side as a rack engaging with said pinion, and traversing the housing, an abutment through which the rod passes, a compression spring carried by the piston-rod near its end and adapted to cushion the piston on its back stroke in conjunction with said abutment, and a hoisting cable drum operatively connected to said shaft.

3. A hydraulic hoist comprising a pressure cylinder, an adjacent housing, a cross-shaft mounted therein, a pinion fixed to the shaft, a piston and rod in said cylinder, the rod being formed on one side as a rack to engage the pinion and traversing the housing, a cable-drum and ratchet secured to the cross shaft at one side of the housing, a bracket projecting from the housing, a pendulum suspended therefrom, and a pawl carried pivotally by the pendulum.

4. In combination with a hydraulic hoist having a shaft, a pinion and drum fixed to the shaft, a reciprocating piston and rod provided with a rack adapted to transmit rotary motion to the pinion and drum, a ratchet connected with said drum, a pendulum pivotally supported adjacent the ratchets periphery, and a pawl carried pivotally by the pendulum, the point of contact of the pawl with the ratchet being practically in line with the pendulum and pawl pivots.

5. In combination with a hydraulic hoist having a shaft, a pinion, drum and ratchet secured to the shaft, a reciprocating piston and rod provided with a rack adapted to transmit rotary motion to the pinion, drum and ratchet, a pendulum pivotally supported adjacent said ratchet, and a pawl carried pivotally by the pendulum and limited in its movements thereby, the pawl having an extended tail-piece as a lever for disengaging the pawl.

6. The combination with the cable-drum and connected ratchet of a hydraulic hoisting jack, of detent mechanism, comprising a pendulum adjacent the ratchet and hung from above the same, a pawl with an extended tail-piece pivoted to the pendulum substantially in line with the point of engagement of the pawl and ratchet and the pendulum pivot, a stop on the pendulum to limit the forward tilt of the pawl, and an adjustable abutment adapted to limit the shift of the pawl in the opposite direct-ion.

7. The combination with the cable-drum and connected ratchet of a hydraulic hoisting jack, of detent mechanism comprising a pendulum pivotally supported adjacent the ratchet periphery, and a pawl carried pivotally by the pendulum, the point of contact of the pawl with the ratchet being substantially in line with a line connecting the pendulum and pawl pivots.

In testimony whereof I affix my signature.

ROY E. CHOATE. 

